BEIJING, Jan. 23 -- Visitors to the World Expo are expected to far exceed 70 million judging by the way tickets are selling, Shanghai Mayor Han Zheng said Friday.

Some 70 million visitors from home and overseas were expected to visit the Expo in Shanghai between May to October, a number that would surpass the 64 million record set at the Osaka Expo in 1970.

"It seems that our 70 million visitors' projection is rather conservative," Han said when meeting Heinz Fischer, the Austrian federal president, in Shanghai Friday. "The real figure may go far beyond that projection as 20 million tickets have already been sold the fair is still about three months away."

There are several kinds of tickets to meet the needs of most people. Sales of ordinary tickets, peak-day tickets, three-day and seven-day tickets have already begun.

Cheaper night tickets will be available from May.

Han said Shanghai would learn from other countries' experiences in hosting Expos to make the world fair in Shanghai a successful, wonderful and unforgettable event.

He also thanked other countries' support and help in improving the event.

Austria would go all out to support the Shanghai World Expo, an event sure to be a splendid occasion for the city to remember, Fischer said.

Many heads of state have already visited the Expo site to check their countries' preparations.

More than 50 heads of state or government have said they will visit Shanghai during the Expo.